Effect of abrasive size on friction and wear characteristics of nitrile butadiene rubber (NBR) in two-body abrasion

Elastomeric seals are prone to failure caused by abrasion during sliding against rough surfaces. This study is devoted to investigate the two-body abrasion wear characteristics of NBR and effect of abrasive size on abrasive wear. The reciprocating abrasive wear tests were performed on a NBR pin against a SiC sandpaper, the abrasive sizes of SiC ranging from very large (200 μm) to small (2.5 μm). The morphologies of the NBR worn surface were examined using scanning electron microscopy and surface profilometry. In addition, the friction coefficients and wear rates were analyzed and compared. The results showed that abrasive size had a significant effect on the wear mechanical and tribological properties of the NBR. Overall, the wear mechanism of NBR transformed from abrasive wear to adhesive wear as the abrasive size decreasing. It is shown that for small abrasives, the friction coefficients decrease with the increasing abrasive size. However, for large abrasives, the reverse trend is observed. This difference is partially explained by the changes of wear mechanisms. The knowledge gained herein provides a better understanding of the rubber degradation and wear mechanism associated with abrasive sizes, and is useful to reduce sealant wear and lengthen their service life.